Frank tiione



Patented Sept. 9, 1890.

; No Model.)

I. THONE. RHBOSTAT.

illsr nn drains as. it a an: 1

FRANK 'lllONl'l, OF OSKALOOSA, ASSIGNOR TO Tlll l llAlVlililYE Eilillj'iitib MANUFAUEL'HING COMPANY, OF DAVENPOR'I, l'O'WA.

Fit-j EGSTi-Ti.

PEGIFICATZQB? forming part of Letters Patent No. 435,985, dated September 9, 1890,

Application filed August 1, 1838- Serial l lo, 281,636. (No model.)

To aZZ whom it may concern.-

Beitlcnown that LFRAN TnoNn, of Oskaloosa, in the county of Mahaskaand State of Iowa, have invented certain new and useful Improvements in Rheostats, of which thefolhighest to lowest strength, or vice versa: The

construction is such that the device may be used with perfect safety with very powerful currents and applied with perfectly satisfactory results to very light or weak currents,

thus obviating difficulties common to most forms of rheostat heretofore employed.

In the drawings, Figure l' is a perspective view of my improved device complete; Fig. 2, a vertical sectional. view through the same on line 3 3 of Fig. 3; Fig. 3, a similar "sectional view on line 2 2 of Fig. 2. i

In the construction of a device of ,this character it is very desirable to avoid a step; by-step change from one degree of resistance to another, as such cha ?go subjects the'coir doctors and instruments to an undue shock,'

which is liable to work to their detriment, are], it is also desirable to have it so simple and durable in construction and of such wide range of capacity that it may be used byun skilled persons with frequency and without great care without danger of breakage crinjury. These ends I attain by the construction set forth below, and illustrated in the drawings, in which- I A indicates a shell or casing, which, for con venience and economy, 1 preferably make of cylindrical form, and which I provide with a base-plate B and a cap or cover C, the former being soldered or brazed to the shell, screwed thereon, or otherwise secured in place, and the cap orcoverbeing serewedin place or otherwise so secured as to permit of ready removal when necessary. The base-plate B is furnished with holes a to receive screws, bolts, or other fastenings by which to secure it in position. ".ihcsheli is furnished on its interior with sheetasbcstus lining I) or other suitable insulating material, shcet-asbestus being preferrcd because of its indcstructibility under high temperatures and its good insulating qualities. The lining 1/ extends overthc ends as well as the side walls of the casing, as

shown in Figs. 2 and 3, and within the lower end of the shell and resting upon the lining is placed a metal disk. 1'), through the center of which is passci'l a bolt E, the stem of which extends through and some distance below the bottom plate 1?. The hole in the baseplate, through which the bolt passes, is en largcd to prevent contmztwiththe belt, which latter carries immediately below the base-- plate a disk or washer c, of sheet-asbestus, n ica, or other good insulator, passes through no endof amctal' strap (1, and is furnished with'a nut c, which latter binds the several parts firmly together. llelow nut c one end of wconducting-wirc- F is coiled about the stern ofthcz'loolt, and "this wire is firmly clamped betweensaid nut and a washer f by a second nut g, thus making a good electrical contact and permanent connection.

Upon the cap or cover 0 is placed a sheet or disk Gr, of asbestus or other'suitable insulating material, and above this atop plate H, having an internally-tln'eaded hole at its center to receive a screw-stein l, which stem is furnished at its upper .end with a crank-handle or winch J, of non-conducting material, or eitectually insulated from the stern, and with a metal hub or collarl. The lower-end of the screw-stem I is advisably, though not necessarily, Burnished with an auger-like disk K, which as the stem is screwed up or down serves to loosen up the pulverulent filling L,-

with which the shell Ais supplied, so that the stem may always move freely and without inaterially compacting the filling beyond its normal condition. The avoidance of a change in the density of the filling is important, for the reasenthatthe conductivity changes with change of density, as is well understood. 'The top plate H is secured in place by tap belts or screws Z, carefully insulated from and passing through the top plate ll and the'eap or cover (3 oi the shell, the intermediate insulating-laycrer, and the insulating lining b, and screwing into a disk or plate M, which is by IOO the lining Z2 insulated from cap or cover C, and has a central opening suihciently large to preclude contact with screw-stem 1.

Above the top plate H, and insulated there from by strips h of sheet-asbestus, mica, or other suitable material, is a raised yoke or cross-piece N, secured by insulated. screws t' to the top plate H and connected by the metal strap (1 with the bolt E, thus aiiording a path for the current outside of the shell or casing A when proper connection is made with yoke on cross-piece N.

A wire or conductor Q is electrically connected with top plate H by a binding-screw P or otherwise.

lhe shell IA is filled with material in a powdered or finely-granulated state capable of resisting a high degree of heat and of conducting an electric current, but offering a veryconsiderable resistance thereto. It is very important that the filling material be proof against high temperatures because of the heat occasioned by high resistance, and that itolfers a very considerable resistance to the passage of an electric current, in order that the device may be utilized for the regulation of powerful currents. Any sub stantially infusible or non-combustible powder or fine granular substancethat is to say, any substance which will not fuse or burn under practical working conditions and which is a poor conductor of electricity-maybe employed; but after many experiments I have adopted and prefer to use a composition consisting of ninety-seven or ninety-eight per cent. of graphite or plumbago and the balance-tirree or two per cent, asthe case may be--of coke in the form of a powder. It is important that both the graphite and the coke be pure, and to this end I find it desirable to wash or soak the coke in sulphuric acid,and subsequently to remove all trace of the acid by washing in pure water. As stated, however, other fillings may be used, very good results being given by the use of graphite alone.

It is apparent that the details of construction admit of considerable variation without I afiecting the substance of my invention--as for instance, by making the lining of the sides and bottom in one piece, of gutta-percha or equivalent material, employing a sliding stem, with or without an actuating-lever to move it longitudinally, substituting a wire for the metallic strap d, and in other ways that will readily suggcstthemselves to the electrician and the mechanic. The shell or casing is made of a length and diameter proportion'ate to the use for which the device is designed, and will in every case be large enough to contain a sufficient quantity of material and length'of column to afford the maximum resistance likely to be required when the whole or substantially the whole, column is i brought intocircuit. vAssuming the device to be in a circuit, and that it is desired to prevent the passage of any material part of access away from bolt E, leaving the entire inter vening body of graphite or other filling as a resistance to the current, and thus el'fectually preventing the passage of any material. or considerable portion thereof. It, now, it be desired to permit the current to pass, the stern I is lowered through the filling material a greater or less distance, as indicated in. Fig. 2, causing the lower end of the stem to approach the head of bolt E and lessening the length of the intervening body of material, the resistance decreasing and the flow of the current increasing as the distance between the stem 1 and bolt E lessens. The length of stem 1 is such that before it shall quite reach the head of E the hub or collar lishall make contact with yoke or cross-piece N," as shown v ments or machinery.

I am aware that pulverized carbon has been employed as aresistance, andthat provision has been made for varying the resistance by varying the degree of compression of the can con. 1 am not, however, aware that it has ever before been proposed to employ as a re- .1

sistance a practically non-combustible dry powder, and this I desire to claim broadly.

Having thus described my invention, ii claim-=- 1. A variable resistance or rheostat-for elec tric circuits, consisting of a body of practically non-combustible matter in the form of a dry powder and circuit connections atoppo site sides or ends of said body.

2. In a variable resistance or rheost-at for electric circuits, the combination of a shell or casing, a body of dry practically non com bustible powder contained therein, and cirwit-connections atv opposite sides or ends of 4 said body, one movable toward andfrorn the other through the mass of powder and adapted by such movement to lessen the distance between the nearest approaching points of the circuit-connections.

3. The herein-described rheostat'or variable resistance, consisting of a shell or casing con taining a powdered substance capable of of fering resistance to the passage of an electric current, a circui't connection at one. end of the shell insulated therefrom but in electrical connection with the powder therein, a cap or cover, a plate having a threaded hole andin sulated from the cap or cover, and a screwstem threaded to fit said hole and adapted to move longitudinally into or throw. l plate B, lining b, disk 1), bolt 13, powder contained in the shell ineoii l cover #13 insulating material G, top tinotion to merelybesring upon'n-nd ..i, and stein i, through. said the compression of the yowder. l (god extending lliilO the filling. 5 5 4. IncombinationwithslieliAfimvinglmsc- The combination oi shell A, provided late B and on (J fillin L insulstin linin with :i rosis'tiiw-fillin lasso JlateB linin b p 7 b 7 w o a :9 W 23 b7 7 b bolt E to late 11 and screw 1, 'zissinq bolt it can or cover U insulation G to) late a 2 P V P i. V 7 i. a a through said plate and into the i1llmg,suoll, and SCl9W-Si1Giil I, provided with screwstantially as described and shown. disk. K. 40

i). The llOIQlibilGSCllbBd rlieostsi, consisting a shell or easing A,oontaining a powdered sting motorist base-plate B, insulated bolt cap or cove if, insulated plate ll, stem 11,

)i'ovidoil with collar or hub I and pissing lire-ugh gplste ll, yoke or cross-piece N,

i suluiod from ists lillooziled in the path of .iuli l sud elect csliy connected with bolt E.

1%.). lo sonibiamtion with. a shell or casing s i sis'lingpowdoreontainedtlierein,cir- 5o opposite circuitco'nneption,Wlioi'eby the "-oonneotions in eleeti'io connection with rent is caused to pass around the resi z; the filling zit SEPtlzll-(itl points, one of said body or filling when the mo oiroi" onsaeeocnoetions being; movable relatively to the tions are brought into close proximl (Flier. and provided ii an agitating device 6. In combination with ell l mipactiog of the powder. 5

croofl. hereunto set myliand in r two Witnesses.

x0 5. In a rheost-at or variable electric resist l ance, the combination of a shell or chamber, 1 o a filling of powgderecl material capalalo of ziir fording a proper resistance to an electric current, a, circuit-connection at each. end llli, I I5 shell or chamber, one movable roletiwl,

the other, a contest hill) or block c2. the movable-contact, and on (luctor placed in the pail-lei block and in electrical. connection sulated bolt or binding device ii m. a with a resisting-powder, insulated piste the and stem 1', passing through .nid plate and provided with screwfiisk K, substantially as shown and described i, 51 l 7. The combination substantially as set forth, of shell A, provided with it i'esis FQANK TllONE. v 

